This is what the SNES outputs in hi-res mode. Due to the analog nature of the TV sets of that time, the vertical lines blend together. This is a trick usually employed by
Genesis games because the graphics hardware can't combine the background/sprite layers.
SNES9x v1.53 has an option called "Blend Hi-Res Images" in its video options; this simulates the TV's blending effect and makes the games
look nicer. It's not really more accurate emulation of the SNES itself though and it can't be detected by games, so it wouldn't matter for TASes.
The SNES renders 512 pixels per line. The game can select twice which backgrounds and sprites are drawn, once for the even-numbered pixels and once for the odd-numbered pixels. When high-res mode is activated, all 512 pixels are sent to the TV. (This is what KDL3 does.) Usually the high-res mode is deactivated so you only see the odd-numbered pixels; this is called the "mainscreen". When "color math" is activated, the even-numbered pixels ("subscreen") can be combined with the odd-numbered pixels. This is how games achieve effects like transparency (the transparent layer is simply only on one screen).
